--- transmission-2.60.org/libtransmission/transmission.h
+++ transmission-2.60/libtransmission/transmission.h
@@ -43,6 +43,7 @@
 
 #include <inttypes.h> /* uintN_t */
 #include <time.h> /* time_t */
+#include <unistd.h> /* off_t */
 
 #if !defined(__cplusplus)
  #ifdef HAVE_STDBOOL_H
